An exhaust system of a diesel engine that comprises a diesel particulate filter (DPF) is capable of physically trapping diesel particulate matter (DPM) in exhaust gas passing through the exhaust system from the engine. This prevents significant amounts of DPM from entering the atmosphere. Soot is one constituent of DPM. Other constituents include the soluble organic fraction (SOF) and ash (i.e. lube oil additives etc.). The trapping of soot by a DPF prevents what is sometimes seen as black smoke billowing from a vehicle's exhaust pipe.
One type of known DPF is marketed by Johnson Matthey Company under the trade name “Continuously Regenerating Trap” or (CRT™). Another type of known DPF is marketed by Englehard Corporation under the trade name DPX™.
DPF's have previously been used in warm climates without forced regeneration. One possible strategy for forced regeneration of a DPF involves using the engine control system to adjust engine fueling in a way that elevates the exhaust gas temperature to a sufficiently high temperature to combust material trapped by the DPF. If such a strategy is to be as transparent as possible to a driver of the vehicle, it generally requires that the vehicle is being operated in a manner that is both compatible with and substantially unaffected by the extra fueling needed to elevate exhaust gas temperature. It is believed fair to say that a successful strategy will introduce a certain amount of complexity into an engine control system.